Segmented switched reluctance electric machine with interdigitated disk-type rotor and stator construction

A method of manufacture of a unipolar current electrical machine having a housing, a stator mounted in the housing, and a rotor, the rotor having a shaft with an axis therethrough and being supported by bearings for rotation about the axis in the housing, the method comprising the steps of:

• (a) selecting from a plurality of individual stator elements the number of stator elements necessary to produce the desired horsepower or kilowatt rating for the electrical machine wherein stator elements are in the form of annular disks comprising a plurality of magnetically isolated magnetic teeth, each stator element having thereon a plurality of electrical windings on each of the stator elements, each winding being associated with a group of magnetic teeth of the stator element, the windings being arranged such that, when energized with a current flowing in the windings, a magnetic flux is created in a first direction;
• (b) selecting from a plurality of individual rotor elements necessary to produce the desired horsepower or kilowatt rating for the electrical machine, wherein the rotor elements are in the form of circular disks comprising a plurality of magnetically isolated magnetic teeth arranged in an annular portion of the circular disks;
• (c) mounting the selected stator elements in the housing such that the elements are spaced apart from each other;
• (d) mounting the selected rotor elements on the shaft such that the rotor elements are spaced from each other and interstitially disposed with the stator elements in an interdigitated manner, so that a magnetic flux path in a second direction is completed through corresponding groups of teeth on the rotor elements and through corresponding groups of teeth on successive stator elements.

A method of operating an electrical machine in a fault tolerant manner in response to a controller, the electrical machine comprising:

• a housing, a stator mounted in the housing, and a rotor, the rotor having a shaft with an axis therethrough and being supported by bearings for rotation about the axis in the housing,
• the stator comprising:
• a plurality of stator elements in the form of annular disks, spaced apart from each other, each stator element comprising a plurality of magnetically isolated magnetic teeth,
• a plurality of electrical windings on each of the stator elements, each winding being associated with a group of magnetic teeth of the stator element, each group of magnetic teeth being arranged at a predetermined angular position with respect to an adjacent group of magnetic teeth,
• each of the windings being arranged such that, when energized with a current flowing in the windings, a magnetic flux is created in a first direction;
• the rotor comprising:
• a plurality of rotor elements, the rotor elements being spaced from each other and interstitially disposed with the stator elements in an interdigitated manner;
• each rotor element being in the form of a circular disk mounted on the shaft, each rotor element comprising a plurality of magnetically isolated magnetic teeth arranged in an annular portion of the circular disk;
• means for completing a magnetic flux path in a second direction through the magnetic teeth of the rotor elements and through corresponding groups of teeth on successive stator elements;
• a modular control unit arranged to individually control electrical energy applied to each winding of each stator element, the control unit comprising:
• a microprocessor controller, a load sensing means, a rotor angle position sensor, and a plurality of stator control modules;
• each stator control module comprising an electrical switching device connected to a winding of the respective stator element and current sensing means to sense current in each winding of the associated stator element and means to generate a corresponding signal to the microprocessor controller;
• the microprocessor controller being responsive to the load sensing means, the rotor angle position sensor, and the signal representing the sensed winding current, to generate control signals to the control modules;
• the microprocessor controller comparing each current signal to a predetermined fault threshold to detect a fault in a winding in a stator element and causing the corresponding control module to deenergize one or more windings in the stator element in response to the detected fault,
• thereby permitting the motor to continue to operate in the presence of a winding fault.